Cranberries are raised in fields or bogs, which are relatively flat areas divided into sections so that the fields can be flooded both to facilitate harvesting and to protect the vines from frost. The cranberry plants form a mat of vines which may be up to twelve or fourteen inches deep. During harvesting, the berries are removed from the vines and float to the surface of the water. The berries are then gathered up for transport to a processing facility.
Traditional methods of harvesting cranberries and the equipment used to implement such methods generally fall into two categories. Both traditional methods have drawbacks which will be described herein later.
The first general method can be characterized as “beating” and is carried out using equipment which includes beaters which are bars mounted on combine-like revolving structures. U.S. Pat. No. 3,672,140 (Burford) discloses equipment based on this principal. As the harvesting vehicle moves through the cranberry bog, a rotating wheel with transverse bars to agitate the cranberry vines, causes the cranberries to detach from the plants. The rotation of the wheel causes the transverse bars to move through the cranberry vines at a speed greater than the vehicle speed at the position of principal contact with the plants. Cranberries float to the surface of the flooded bog and are gathered up. U.S. Pat. No. 4,501,111 issued to Abbott describes another harvester unit which uses such a rotating wheel approach.
The second general method can be characterized as picking or raking. U.S. Pat. No. 2,524,631 (Minutillo) describes a harvesting machine based on this method. A series of combs mounted on a rotating wheel is moved through the cranberry plants to detach the cranberries from the vines. U.S. Pat. No. 5,067,047 (Rosset) discloses harvesting equipment which employs vertically-oscillating tines to strip the cranberries from the vines. Rosset then collects the stripped cranberries through a vacuum suction unit.
As mentioned above, the methods and equipment which are used for cranberry harvesting have certain drawbacks. As in any commercial endeavor, increased productivity is in general a desired performance. Typical harvesting rates for the cranberry-harvesting equipment commonly used today is on the order of 0.5 acres per hour, with maximum rates being about 1.5 acres per hour. Productivity is also affected by the fraction of the fruit which is removed from the vines during harvesting. A higher fraction yields higher productivity.
Some of this equipment is quite “aggressive” in how it treats the cranberry plants, often resulting in damage both to harvested fruit as well as the vines. In addition, much of the equipment used today includes a number of moving parts, often driven by hydraulic equipment. The operation of hydraulic equipment during harvesting creates the risk of the fruit becoming contaminated with hydraulic fluid. Also, the complexity of the equipment translates into increased maintenance cost.
Finally, for cranberries which are sold as fresh fruit rather than processed into juice or other consumer food products, not only is it advantageous to prevent damage to the fruit, it is also of great benefit to avoid wetting the fruit during harvesting. As mentioned above, the fields or bogs are flooded, allowing the fruit which has been separated from the plants to float, thereby facilitating the collection of the fruit. However, the fruit, being now wet, is subject to the growth of fungus or requires the additional costly step of drying in order to deliver fresh, unblemished fruit to the market. Because of this, it is advantageous to dry-harvest cranberries to avoid these problems or costs.
Therefore, there is a need for simple, rapid and efficient, low-cost method and apparatus to harvest cranberries.